1. Field of the Invention
The present invention relates to an image reading apparatus for reading a bookform document which makes it easy to place a bookform document on an accurate position of a document table in face-up opened state.
2. Description of the Prior Art
In a conventional image reading apparatus, which reads a document placed opened and face-up on a document table, center marks for positioning the document are arranged on two positions, front-ward and backward of the document table, and positioning of the document can be executed by fitting the document bound potion with the marks.
Further, in a conventional image reading apparatus wherein a document is placed opened and face-down, scales indicating sizes are arranged on two positions, front-ward and sideward of the document table, and the positioning of a document can be executed by fitting the document corners with the scales.
However, according to the above-mentioned conventional image reading apparatus wherein a document is placed opened and face-up, when a document having a thickness such as encyclopedia is placed, there has been a problem that positioning the document tends to be inaccurate due to an unevenness of the height of document""s bound portion and the height of the center marks drawn on the document table. Especially, the problem has been serious when the document table is moved vertically, and the document is unstable. Furthermore, concerning a small size document such as a paperback, there has been the same kind of problem as there is a distance between the documents"" bound portion and the center marks. Moreover, according to the above-mentioned image reading apparatus in which a document is placed opened and face-down, when a thick book is placed on the document table, there has been the same kind of problems as the document""s bound portion lifts up from a glass plane of the document table.
The present invention is made to solve the abovementioned problem. An object of the present invention is to provide an image reading apparatus wherein an easy and accurate positioning is executed concerning a document placed opened and upward to be read out, even though the document has a thickness such as a book.
In accomplishing the above-mentioned object, the image reading apparatus wherein a document placed opened and face-up is read out, comprising a document table on which a document is placed, an image reading means for reading out an image of the document placed on the document table, a projection means for projecting the document upper plane image on the image reading means, and a indication means for positioning the document on the document table based on a comparison with a mirror image of the document upper plane mirrored on the projection means.
In this construction, the image reading means reads out an image of a document placed on the document table opened and face-up and also the document upper plane image mirrored on the image reading means by the projection means. The indication means is drawn on the projection means for positioning a document on the document table. Therefore, an operator can execute positioning of a document on the document table easily and accurately by comparing the indication means drawn on the projection means and a mirror image of the document upper plane mirrored on the projection means even though the document is thick such as an encyclopedia or it is small size such as a paperback.